Study On Biological Nitrogen Removal By Nitrification-ANAMMOX Process

It is always a difficult problem to realize high-efficient and low-consumption disposal of high ammonia nitrogen and low C/N ratio wastewater in the wastewater treatment field. In recent years, anaerobic ammonium oxidation as a novel biological nitrogen removal process has become a research focus in this field, which had been widely studied and has began to be applied in wastewater biological nitrogen removal field at broad. In this paper, the author used high-strength synthetic ammonium wastewater as the research target to separately research the technology of a long MCRT nitrification and quick start-up anaerobic ammonium oxidation process, and based on which, we successfully realized the high efficient nitrogen removal with nitrification-ANAMMOX combined process. The conclusions are as follows:1. By means of keeping the microbe long sludge age (106 d), through adjusting aeration capacity (0.040m³/h) and controlling dissolved oxygen (below 1.0mg/L) in the reactor, it is successfully realizedthe ratio of NH₄⁺ - N/NO₂^- - N in the high-strength ammonium wastewater outflow from the nitrite reactor reaching 1:1.2. Utilizing the oxygen consumption characteristic in ammonium oxidation, it can realize the inflow dissolved oxygen below 0.05mg/L in the ANAMMOX reactor, which provided the precondition and guarantee for realizing high efficient biological nitrogen removal in anaerobic ammonium oxidation process.3. The experiment results showed that anaerobic ammonium oxidation could realize high efficient nitrogen removal. The maximal ammonia, nitrite and total nitrogen removal rate were 99.91%, 99.86%, 91.35% respectively, the average removal rate of ammonia, nitrite and total nitrogen were over 87.85%, 95.5%, 81.5% respectively.4. The experiment results showed that total nitrogen removal volumetric loading could reach 0.9 kgTN/m³Â·d with the use of high volumetric loading start up reactor in a short time, which is higher than 0.215kg/(m³ ? d) under low volumetric loading start up stage. It has not come restraint by nitrite that usually comes up during low volumetric loading start up reactor influent concentration being more than 300mg/L.5. The experiment results showed that the combined process has successfully realized high efficient biological nitrogen removal under the condition of total nitrogen volumetric loading being 0.358kgTN/(m3 ? d), using pure ammonium synthetic wastewater as research target. During the experiment period, the maxima] ammonia and total nitrogen removal rate could reach 99.9%, 90.8% respectively, the average removal rate of ammonia and total nitrogen were 96.1%, 76.1% respectively. The outflow substrate ratio of ammonium to nitrite from the nitrite reactor restrains the nitrogen removal rate. The nitrogen removal rate is about 60% when the ratio of ammonium to nitrite is controlled between 0.62 and 0.77, and about 80% when the ratio is controlled between 0.77 and 1.33.6. Comparative experiments were done by use of synthetic wastewater of treated domestic wastewater and untreated domestic wastewater containing ammonium bicarbonate and nitrite. As for the results TN removal rates were 78.63% and 76.57% respectively, which showed that the activities of ANAMMOX bacteria were not affected by the existence of organic matter. High-strength ammonium and low C/N ratio wastewater can realize high efficient biological nitrogen removal with anaerobic ammonium oxidation.7. The observation results of optical microscope and SEM showed that, dominant nitrococcus could be spherical bacteria (Nitrosococcus). Anaerobic ammonium oxidation bacteria were one combined body of the bacillus, spirobacteria and filamentous bacteria. The bacteria of granular in reactor began to autolyze with extension of time. The species of granular exterior bacteria is abundant; the exterior surface of which is smooth and its activities is high. Under theoretical hypothesis, the maximum specific microbial incremental rate was 0.0779d"1 and equivalent multiplication time was 9 days.